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This project is mirrored from https://github.com/haskell/Cabal. Pull mirroring updated .
  1. Nov 22, 2016
  2. Nov 20, 2016
  3. Nov 18, 2016
  4. Nov 17, 2016
  5. Nov 16, 2016
  6. Nov 15, 2016
  7. Nov 14, 2016
  8. Nov 13, 2016
  9. Nov 12, 2016
    • Duncan Coutts's avatar
      Update test case BuildTargetErrors/non-buildable · 543b28a1
      Duncan Coutts authored
      Since this fixes #3858
      543b28a1
    • Duncan Coutts's avatar
      Fix implementation of addBuildableCondition · 40d1b4f1
      Duncan Coutts authored
      The addBuildableCondition function was added to solve the problem with
      "buildable: False". The problem was that we would solve or check
      dependencies on the basis of the component in question being needed, and
      then at the end discover that the component is actually not buildable at
      all, and if we'd known that up front we would not have solved for the
      component's dependencies.
      
      The trick that addBuildableCondition does is a syntactic transformation,
      from components like:
      
      executable blah
        buildable: False
        build-depends: foo >= 1, bar < 2
        something-else: whatever
      
      to:
      
      executable blah
        -- empty!
      
      Or at least, that's the intention. In the above situation the
      implementation of addBuildableCondition returns an empty CondNode:
      
      CondNode mempty mempty []
      
      The type at which mempty is used is important here. This transformation
      is used in two places: one in the solver and the other in finalizePD.
      In the solver the mempty is used at types from the PackageDescription:
      Library, Executable, TestSuite etc. So in this case the transformation
      works fine we end up with empty executables, test suites etc.
      
      In finalizePD however the mempty gets used at type PDTagged (which is
      sort of a union of Library, Executable etc plus none/null) and the
      mempty for PDTagged is PDNull which means it does not even specify
      which component we're referring to. So effectively that means instead of
      ending up with an empty executable in the above example, we end up
      deleting the executable entirely!
      
      This was a change in behaviour. Prior to adding addBuildableCondition
      the result of finalizePD would include non-buildable components and the
      rest of the build system infrastructure was set up to skip over them
      when building. The change was not noticed precisely because the rest of
      the system was already set up to ignore non-buildable components.
      
      This is not however a benign change in behaviour. In particular in
      cabal-install in the install plan we end up completley forgetting about
      all the non-buildable components. This means we cannot even report that
      components are non-buildable when users ask to build them, because we've
      completely forgotten that they exist.
      
      So this patch keeps the original addBuildableCondition for use by the
      solver since the solver uses it at sensible monoid types. The patch adds
      a special version for the PDTagged type which changes the transformation
      so that in the above example we end up with:
      
      executable blah
        buildable: False
        something-else: whatever
      
      So we've stripped out all the build-depends but we keep everything else,
      including of course the "buildable: False".
      40d1b4f1
  10. Nov 11, 2016
  11. Nov 09, 2016
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